fix: do not mark time traveling blocks as bad

CHANGELOG.md

@@ -35,6 +35,8 @@
 
 ### Fixed
 
+- [#6241](https://github.com/ChainSafe/forest/pull/6241) Fixed a sync issue that is caused by time traveling block(s).
+
 ## Forest v0.30.3 "Trishul"
 
 This is a non-mandatory release that brings important enhancements in Forest's tooling capabilities.

src/chain_sync/bad_block_cache.rs

@@ -31,6 +31,7 @@ impl BadBlockCache {
 
     pub fn push(&self, c: Cid) {
         self.cache.push(c.into(), ());
+        tracing::warn!("Marked bad block: {c}");
     }
 
     /// Returns `Some` if the block CID is in bad block cache.

src/chain_sync/chain_follower.rs

@@ -230,6 +230,7 @@ pub async fn chain_follower<DB: Blockstore + Sync + Send + 'static>(
         let state_machine = state_machine.clone();
         let state_changed = state_changed.clone();
         let tasks = tasks.clone();
+        let bad_block_cache = bad_block_cache.clone();
         async move {
             loop {
                 state_changed.notified().await;
@@ -256,6 +257,7 @@ pub async fn chain_follower<DB: Blockstore + Sync + Send + 'static>(
                             network.clone(),
                             state_manager.clone(),
                             stateless_mode,
+                            bad_block_cache.clone(),
                         );
                         tokio::spawn({
                             let state_machine = state_machine.clone();
@@ -679,16 +681,8 @@ impl<DB: Blockstore> SyncStateMachine<DB> {
     // Remove all bad tipsets from the tipset map.
     fn mark_bad_tipset(&mut self, tipset: Arc<FullTipset>) {
         let mut stack = vec![tipset];
-
         while let Some(tipset) = stack.pop() {
             self.tipsets.remove(tipset.key());
-            // Mark all blocks in the tipset as bad
-            if let Some(bad_block_cache) = &self.bad_block_cache {
-                for block in tipset.blocks() {
-                    bad_block_cache.push(*block.cid());
-                }
-            }
-
             // Find all descendant tipsets (tipsets that have this tipset as a parent)
             let mut to_remove = Vec::new();
             let mut descendants = Vec::new();
@@ -837,6 +831,7 @@ impl SyncTask {
         network: SyncNetworkContext<DB>,
         state_manager: Arc<StateManager<DB>>,
         stateless_mode: bool,
+        bad_block_cache: Option<Arc<BadBlockCache>>,
     ) -> Option<SyncEvent> {
         tracing::trace!("SyncTask::execute {self}");
         let cs = state_manager.chain_store();
@@ -853,8 +848,14 @@ impl SyncTask {
                 is_proposed_head,
             } => {
                 let genesis = cs.genesis_tipset();
-                match validate_tipset(state_manager.clone(), cs, tipset.deref().clone(), &genesis)
-                    .await
+                match validate_tipset(
+                    state_manager.clone(),
+                    cs,
+                    tipset.deref().clone(),
+                    &genesis,
+                    bad_block_cache,
+                )
+                .await
                 {
                     Ok(()) => Some(SyncEvent::ValidatedTipset {
                         tipset,

src/chain_sync/tipset_syncer.rs

@@ -3,6 +3,7 @@
 
 use std::sync::Arc;
 
+use crate::chain_sync::BadBlockCache;
 use crate::networks::Height;
 use crate::shim::clock::ALLOWABLE_CLOCK_DRIFT;
 use crate::shim::crypto::SignatureType;
@@ -101,6 +102,7 @@ pub async fn validate_tipset<DB: Blockstore + Send + Sync + 'static>(
     chainstore: &ChainStore<DB>,
     full_tipset: FullTipset,
     genesis: &Tipset,
+    bad_block_cache: Option<Arc<BadBlockCache>>,
 ) -> Result<(), TipsetSyncerError> {
     if full_tipset.key().eq(genesis.key()) {
         trace!("Skipping genesis tipset validation");
@@ -124,12 +126,18 @@ pub async fn validate_tipset<DB: Blockstore + Send + Sync + 'static>(
                 chainstore.add_to_tipset_tracker(block.header());
             }
             Err((cid, why)) => {
-                warn!(
-                    "Validating block [CID = {}] in EPOCH = {} failed: {}",
-                    cid.clone(),
-                    epoch,
-                    why
-                );
+                warn!("Validating block [CID = {cid}] in EPOCH = {epoch} failed: {why}");
+                match &why {
+                    TipsetSyncerError::TimeTravellingBlock(_, _) => {
+                        // Do not mark a block as bad for temporary errors.
+                        // See <https://github.com/filecoin-project/lotus/blob/v1.34.1/chain/sync.go#L602> in Lotus
+                    }
+                    _ => {
+                        if let Some(bad_block_cache) = bad_block_cache {
+                            bad_block_cache.push(cid);
+                        }
+                    }
+                };
                 return Err(why);
             }
         }